We report the discovery of a specimen of Tenontosaurus tilletti from the Cloverly Formation that bears lesions we interpret as bite marks of Deinonychus antirrhopus. Some of the bite marks are in the form of exceptionally deep punctures through the long bone cortices. These provide a rare opportunity to estimate the bite-force capacities of this taxon through tooth indentation simulations. These experiments showed that approximately 4100 N of bite force were required to generate one of the bite marks, and 8200 N would have been generated simultaneously at a distal-most tooth position. These values are higher than those reported for large carnivoran mammals but similar to values recorded for comparably sized crocodilians. Although current evidence does not indicate how D. antirrhopus actually used its claws and teeth to acquire prey resources, it is clear that large individuals were capable of generating forces great enough to bite through bone.

Disarticulated dinosaur bones have been discovered in a fossiliferous lens in the Labirinta Cave, southwest of the town of Cherven Bryag, in NW Bulgaria. This cave is formed within marine limestones belonging to the Kajlâka Formation of Latest Cretaceous age. Associated fossils and Sr isotopy suggest that the fossiliferous sediments belong to the uppermost part of the Upper Maastrichtian. The dinosaur bones discovered in this lens include the distal portion of a left femur, a right tibia, the proximal part of a right fibula, a left metatarsal II, the second or third phalanx of a left pedal digit IV, the proximal end of a second metacarpal, and a caudal centrum. All the bones undoubtedly belong to ornithopod dinosaurs and more accurately to representatives of the hadrosauroid clade. All belong to small-sized individuals, although it cannot be assessed whether they belong to juveniles or small-sized adults, pending histological analyses. Hadrosauroid remains have already been discovered in Late Maastrichtian marine sediments from western, central and eastern Europe, reflecting the abundance of these dinosaurs in correlative continental deposits. Indeed, hadrosauroids were apparently the dominating herbivorous dinosaurs in Eurasia by Late Maastrichtian time.

In the last 30 years, the Two Medicine Formation of western Montana has provided a wealth of information about dinosaur reproductive biology. Here, we describe a fossil egg-bearing stratum that occurs approximately 105 m above the base of the formation. This site in the Sevenmile Hill outcrops south of Choteau, Montana, lies immediately above a volcanic tuff and bentonite, dated as 80.0 Ma. Spherulitic eggshells from a quarry at this locality are similar to Spheruprismatoolithus candensus Bray, 1999, which were assigned to the oofamily Prismatoolithidae. However, we refer this eggshell to the Spheroolithidae Zhao, 1979, as Spheroolithus choteauensis, oosp. nov. The quarry also produced Triprismatoolithus stephensi, oogen. et oosp. nov. These symmetrical 30 mm 75 mm prismatic eggs exhibit three structural layers of calcite and round tubercles on the shell surface. Four additional ootaxa occurred at the First Find Microsite (OTM 99-19): Prismatoolithus hirschi, oosp. nov.; Tubercuoolithus tetonensis, oogen. et oosp. nov.; Continuoolithus canadensis Zelenitsky et al., 1996; and Krokolithes Hirsch, 1985. Spheroolithus choteauensis, T. stephensi, P. hirschi, T. tetonensis, and Krokolithes are unique to the lowermost Two Medicine Formation, whereas C. canadensis may occur elsewhere in the middle and upper strata of the Two Medicine and Oldman formations of Montana and Alberta, respectively. Although poorly represented by dinosaur osteological remains, the lower Two Medicine Formation locality yields egg types that suggest a significant difference in faunal composition compared to the middle and upper portions of the formation.

The extinction pattern of the Maastrichtian indicates that long-term and short-term events contributed to the Cretaceous–Tertiary (K–T) mass extinction at 65 Ma. However, it is not clear how the impact events are linked with the extinction selectivity; e.g. non-avian dinosaurs became extinct, whereas birds survived. The post-impact air quality is discussed, and attention is focused on the then land vertebrates. Although ground-level (tropospheric) O3 is a powerful irritant on the order of 0.1 ppm toxicity, the presence of ground-level O3 has hardly been considered since the K–T impact theory was reported about 30 years ago. Under the post-impact conditions reconstructed by simulating the carbon cycle (including isotope balance) and impact chemistry, a trajectory model suggests that the then photochemical reactions formed ground-level O3 whose concentration was apparently low at ~ 1.0 ppm, but it is much greater than the current level of ~ 0.04 ppm: that is, an O3 concentration above the health-threatening level persisted on the ground after the K–T impact. All land vertebrates must have suffered from respiratory O3 irritation at the time. However, analysis suggests that variables of O3 characteristics – hourly variation, short half-life in water and decomposition due to catalytic effects in soil – were randomly combined with variables of lifestyle features such as habitat, torpor, etc. to form new variables (i.e. survival rates): a high survival probability for amphibians; middle/high probabilities for semi-aquatic reptiles, mammals and birds; low/middle probabilities for marsupials and terrestrial reptiles; and a zero probability for non-avian dinosaurs.

An avian tarsometatarsal (TMT) skeleton spanning from the base of toes to the intertarsal joint is a compound bone developed by elongation and lateral fusion of three cylindrical periosteal bones. Ontogenetic development of the TMT skeleton is likely to recapitulate the changes occurred during evolution but so far has received less attention. In this study, its development has been examined morphologically and histologically in the chick, Gallus gallus. Three metatarsal cartilage rods radiating distally earlier in development became aligned parallel to each other by embryonic day 8 (ED8). Calcification initiated at ED8 in the midshaft of cartilage propagated cylindrically along its surface. Coordinated radial growth by fabricating bony struts and trabeculae resulted in the formation of three independent bone cylinders, which further became closely apposed with each other by ED13 when the periosteum began to fuse in a back-to-back orientation. Bone microstructure, especially orientation of intertrabecular channels in which blood vasculature resides, appeared related to the observed rapid longitudinal growth. Differential radial growth was considered to delineate eventual surface configurations of a compound TMT bone, but its morphogenesis preceded the fusion of bone cylinders. Bony trabeculae connecting adjacent cylinders emerged first at ED17 in the dorsal and ventral quarters of intervening tissue at the mid-diaphyseal level. Posthatch TMT skeleton had a seemingly uniform mid-diaphysis, although the septa persisted between original marrow cavities. These findings provide morphological and histological bases for further cellular and molecular studies on this developmental process

Recent field efforts in the Mahajanga Basin of northwestern Madagascar have recovered a diverse Late Cretaceous terrestrial and freshwater vertebrate fauna, including a growing diversity of avialans. Previous work on associated bird skeletons resulted in the description of two named avialans (Rahonavis, Vorona). Other materials, including two synsacra and numerous appendicular elements, represent at least five additional taxa of basal (non-neornithine) birds. Among the materials described herein are two humeri tentatively referred to Rahonavis and numerous elements (e.g., humeri, ulnae, tibiotarsi, tarsometatarsi) assigned to Vorona. A near-complete carpometacarpus exhibits a minor metacarpal that exceeds the major metacarpal in length, documenting an enantiornithine in the fauna. Moreover, two additional, small humeri, an ulna, a femur, and a tarsometatarsus also compare favorably with enantiornithines. Finally, two other isolated humeri and a synsacrum are referable to Ornithurae. The latter specimen is notable in the presence of distinct, transversely oriented lumbosacral canals along the inner surface of the bony neural canal. This reveals for the first time a hard-tissue correlate of an anatomical specialization related to increased sensorimotor integration, one likely related to the unique form of avialan bipedal locomotion. Bird fossils recovered from the Maevarano Formation document one of the most size- and phylogenetically diverse Cretaceous-age Gondwanan avifaunas, including representative (1) basal pygostylian, (2) enantiornithine, (3) nonenantiornithine, ornithothoracine, and (4) ornithurine taxa. This Maastrichtian avifauna is notable in that it demonstrates the co-existence of multiple clades of basal (non-neornithine) birds until at least the end of the Mesozoic.

Godefroit, P. & Lambert, O. 2003. A re-appraisal of Craspedodon lonzeensis Dollo, 1883 from the Upper Cretaceous of Belgium: the first record of a neoceratopsian dinosaur in Europe? Bulletin de l'Institut royal des Sciences naturelles de Belgique, Sciences de la Terre 77: 83–93.

Necker, R. 2005. The structure and development of avian lumbosacral specializations of the vertebral canal and the spinal cord with special reference to a possible function as a sense organ of equilibrium. Anatomica Embryologica 210(1): 59-74.

Walker, C. A. 1981. New subclass of birds from the Cretaceous of South America. Nature 292:51-53.